A typical communication base station includes a digital unit and a radio unit, which are installed in a single physical system. Such a system has limitations in cell design optimization because it is required to deploy the base station including all processing units in each cell. To solve this problem, a plurality of antennas is connected to one base station for forming a cell in a desired design.
This may enable efficient cell design, but it is difficult to maximize system capacity. Accordingly, there is a demand for developing new base station structures and methods of transmission in order to maximize radio capacity. Joint transmission has been proposed and used to allow at least two neighboring base stations to simultaneously send the same signal or data to a terminal. Using joint transmission, signal quality can be improved by about twice, or spatiotemporal channel coding gain can be attained.
Although joint transmission improves terminal quality, it uses a large amount of radio resources because all of base stations performing joint transmission require resources.
Consequently, overall performance may be degraded when the number of users increases due to lack of radio resources to be used.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.